"In the formulae (IX) and (X), examples of the aromatic hydrocarbon group represented by Ar5 are phenyl group, biphenylyl group, terphenylyl group, naphthyl group, anthryl group, pyrenyl group, fluorenyl group, 9,9-dimethyl-2-fluorenyl group, azulenyl group, triphenylenyl group, chrysenyl group, and a group of the following formula (XI): wherein R15 is a hydrogen atom, an alkyl group which may have" . . . . .